BQ40Z80EVM-020: bqstudio and MCU command control mismatch

Gary Jiang

Part Number: BQ40Z80EVM-020
Other Parts Discussed in Thread: BQ40Z80, BQSTUDIO

Hi team,

My customer now use our BQ40Z80EVM in their vacuum robot 4S BMS project.

They send cell voltage read command to BQ40Z80 via bqstudio, and the data read back is correct.

But when the device is reset, then they use their MCU to send the code 0x0071 to read the cell voltage message, the data read back is incorrect.

Besides, if the device is reset, and first time read is executed by bqstudio, then send 0x0071 to BQ40Z80, the read back data is back to correct.

There is another issue:

When they use bqstudio, all operation is correct. But after reset, and first read operation is executed by bqstudio, then they can use 0x0071 command to read back cell voltage. But they send 0x0072 and get back wrong data.

Can you please help me with these two issue? Is there any command need to be sent after the reset?

Thanks for your help.

Gary

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Gary,

What kind of reset are you talking about? Can they see the same problem if they only use bqStuio to read back all the cell voltages?

Andy

0 Gary Jiang over 5 years ago in reply to Andy Liu (BMS)

TI__Intellectual 980 points

Hi Andy,

Hardware reset(Wake button, S1) on the EVM board.

If they only use bqStudio, all function works well. But they can't find any code tips about this issue. So they want to ask if they need to add additional code between BQ40Z80 wake up and MCU read command?

Thanks!

0 Andy Liu (BMS) over 5 years ago in reply to Gary Jiang

TI__Guru 52115 points

Hi Gary,

The purpose of pushbutton S1 is to wake up bq40z80 from shutdown. My suggestion is to wait a few seconds (e.g. 5s) after the S1 is pressed. Also, I would suggest their host only sends one 0x0071 command per second since these measurements only update once per second.

Andy

0 Gary Jiang over 5 years ago in reply to Andy Liu (BMS)

TI__Intellectual 980 points

Hi Andy,

Thank you. And there is another issue:

customer finds on TRM that COV threshold is all related to temp. I think this should be an error, and the unit is still "mV". But I need your confirm. Please see of this is an typo, thank you!

0 Andy Liu (BMS) over 5 years ago in reply to Gary Jiang

TI__Guru 52115 points

No. These are not typos. See Section 3.4 Cell Overvoltage Protections for the details.

Andy

Power management

Power management forum

BQ40Z80EVM-020: bqstudio and MCU command control mismatch